Stents are generally cylindrically shaped prosthetic implants functioning to hold open and sometimes expand a segment of a blood vessel or other anatomical lumen. They are particularly suitable for supporting and preventing a torn or injured arterial lining from occluding a fluid passageway. Stents are typically formed of a cylindrical metal “mesh type” structure that can expand when pressure is internally applied. Alternatively, they can be formed of wire wrapped into a cylindrical shape.
Stents can be used in a variety of tubular structures in the body including, but not limited to, arteries and veins, ureters, common bile ducts, and the like. Stents are used to expand a vascular lumen or to maintain its patency after angioplasty or atherectomy procedures, overlie an aortic dissecting aneurysm, tack dissections to the vessel wall, eliminate the risk of occlusion caused by flaps resulting from the intimal tears associated with primary interventional procedure, or prevent elastic recoil of the vessel.
Stents may be utilized after atherectomy, which excises plaque, or cutting balloon angioplasty, which scores the arterial wall prior to dilatation, to maintain acute and long-term patency of the vessel. Stents may be utilized in by-pass grafts as well, to maintain vessel patency. Stents can also be used to reinforce collapsing structures in the respiratory, biliary, urological, and other tracts.
A stent fabrication method and apparatus is described in U.S. Pat. No. 5,855,802. This patent discloses a method for forming a tubular article having a perforated annular wall, which includes the steps of coating the exterior and interior cylindrical surfaces of a tubular member with photoresist, exposing selected portions of the photoresist coated surfaces to light, developing the coating, and then etching the coating to remove unexposed portions of the coating and immediate underlying portions of the annular wall to form a tubular article having a wall structure defined by a skeletal framework. This patent also discloses an apparatus for exposing the light sensitive coating disposed on the tubular member. The method and apparatus embodying this patent are particularly suitable for forming stents that support the walls of weak human arteries.
U.S. Pat. No. 5,902,475 describes a method of fabricating a stent by processing a tubular member. The method includes the steps of coating the outer surface of the tubular member with photosensitive resist, exposing a selected portion of the outer surface to a light source, immersing the tubular member in a resist developer, and then processing the treated tubular member by electrochemical etching process.
Stent fabrication methods and devices are also described, for example, in U.S. Pat. Nos. 5,421,995, 5,741,429, 5,766,238, 6,027,863, 6,056,776, and 6,107,004. There, however, remains a continuing need for improved apparatuses and methods for fabricating stents.